Coil-less relay for use on bus bars



Aug. 30, 1966 R. CASTENSCHIOLD COIL-LESS RELAY FOR USE ON BUS BARS FiledMay 19, 1965 Fla/42 lNVENTOR: 499W 'oure/vsrw/aao BY g i 5/ EORNEYSUnited States Patent 3,270,163 COIL-LESS RELAY FOR USE ON BUS BARS RenCastenschiold, New Vernon, N.J., assignor to Automatic Switch Company,Florham Park, N..l'., a corporation of New York Filed May 19, 1965, Ser.No. 456,917 4 Claims. (Cl. 335-204) This invention relates to relays forsensing current flow in electrical conductors, and more particularly tosuch a relay adapted to be mounted directly on a bus bar.

Various types of current-sensing relay arrangements are known in which apair of electrical contacts are to be actuated when current flow exceedsa preselected value. In one type, a relay coil is connected in serieswith the conductor in which current fiow is to be measured, the relaycontacts being closed when current flow through the coil exceeds thepreselected value. Use of such a series-connected coil is generallylimited to installations in which the current does not exceed 100amperes. In other type of arrangement, the conductor being monitored isprovided with a step-down current transformer, i.e., a transformer coilsurrounds the conductor, and the transformer coil is connected to thecoil of a relay. In certain situations, such as Where a time delay isdesired, a heater element is connected in series with the conductorbeing monitored, and a pair of contacts is mounted adjacent to theheaterelement, one of the contacts being mounted on a bimetallic stripand adapted to engage the other when the temperature of the heaterelement reaches a predetermined value.

It is an object of the present invention to provide a relay, for sensingcurrent flow in a bus bar, which does not employ a heater element, orany kind of coil whatsoever.

It is another object of the invention to provide a current-sensing relaywhich can quickly and easily be mounted directly on a bus bar.

It is another object of the invention to provide such a relay which canbe made sensitive enough to react to relatively low current values, butwhich can nevertheless withstand high currents without injury.

It is a further object of the invention to provide such a relay whichoperates in response to either A.C. or DC. currents.

It is still another object of the invention to provide such a relaywhich can be readily manufactured on an economic basis, and which can bemade in varying sizes to fit all known bus bars.

To accomplish these objectives, the invention employs a U-shaped metalrelay core adapted to straddle a bus bar. An armature is pivotallyarranged at the free end of one core arm, and adapted to swing into andout of enegagement with the other core arm, 'a spring normallymaintaining the armature in the latter condition. The armature isreadily removable from the core, so that the core can he slipped on toand oh a bus bar, but means are provided for preventing accidentalremoval of the armature. Thus, the U-shaped core and the armaturesurround the bus bar, thereby eliminating the need for relay coils,transformer coils, or similar expedients.

The invention will now be described in detail with reference to theaccompanying drawings, in which:

FIG. 1 is a front elevational view of a relay according to the presentinvention;

FIG. 2 is a vertical cross-sectional view along line 22 of FIG. 1;showing the relay in deenergized condition;

FIG. 3 is a rear elevational view of the relay;

FIG. 4 is an enlarged fragmentary view, partially in cross-section, thecross-sect on portion being taken along line 44 of FIG. 3, showing therelay in energized condition;

3,270,163 Patented August 30, 1966 "ice FIG. 5 is an enlargedfragmentary rear elevational view of the upper end of one of the arms ofthe relay core; and FIG. 6 is an enlarged fragmentary top plan view ofthe relay armature on its seat.

I The relay chosen to illustrate the present invention comprisesgenerally a U-shaped core 10, and an armature 11. The core is formedfrom an initially-flat strip of metal, such as sheet steel, bent alongtwo longitudinallyspaced-apart transverse lines to form a 'U-s'hapedelement having two arms 12 and 13. The core is preferably an integralelement, rather than a laminated element in Order to simplify changes inthe manufacturing procedure when cores having differing dimensions areto be formed.

The arm 12 is accommodated by a slot 14 in one face of a mounting block15 of insulation material. The slot 14 is at least as deep as thethickness of the arm 12 so that the inner face of the arm is flush withor beneath the corresponding face of the block. Screws 16, or othersuitable fastening means, extend between the block 15 and arm 12 andsecure the core to the block. The block 15, and hence the core 10, aresecured to a bus bar 17 by means of screws 18 passing through holes inthe block and threaded into tapped holes in the bus bar. A pair ofrelatively rigid U-shaped members 21 of insulation material straddle thebus bar -17 and completely insulate it from the core 10. The legs of theinsulating members 21 between the bus bar and the block are providedwith appropriately positioned holes (not shown) through which the screws18 pass.

The length of the arms 12 and 13 exceed the corresponding dimension ofthe bus bar 17 so that the free ends of the arms extend beyond the upperface of the bus bar. The free end of arm 13 is provided with a notch(see FIG. 5) defining a pair of shoulders 22 and an armature seat 23between them, the seat 23 serving as the fulcrum about which thearmature 11 pivots.

The armature 11 extends from the arm 13 to and past a point directlyabove the free end of arm 12. The width of the armature is about equalto the width of the arm 13. The armature is provided with an integraltongue 24, having a reduced width compared to the armature, extendinginto the slot between the shoulders 22 at the free end of arm 13 andresting upon the armature seat 23. The reduced width of the tongueresults in the formation of a pair of shoulders 26 on the armature (seeFIGS. 4 and 6) adjacent to arm 13. The tongue 24 is provided with a bendto define a tongue extension 25 positioned at an angle to the armature11 slightly greater than The armature 11, tongue 24, and extension 25are advantageously formed from a single strip of metal, such as sheetsteel.

Location of the tongue 24 between the shoulders 22 prevents movement ofthe armature 11 with respect to the core 10 in a leftward or rightwarddirection as viewed in FIG. 6. Furthermore, abutment of shoulders 26 onthe armature against shoulders 22 on arm 13 prevents movement of thearmature with respect to core 10 in a rightward direction in FIG. 4. Inaddition, abutment of the upper end of tongue extension 25 against thearmature seat 23 prevents movement of the armature with respect to thecore in a leftward direction in FIG. 4. The abutments described above donot, of course, interfere with the pivotal movement of the armatureabout the seat 23. No means has been described thus far, however, forpreventing the armature and tongue from being lifted off the seat 23.Such a means must perform its function without interfering with thepivotal movement of the armature, and must be readily manipulable sothat the armature can be quickly and easily removed from its operativeposition when the relay is to be mounted on or removed from a bus bar.The present invention provides just such a means.

Threaded into the extension are one or more screws 29, two such screwsbeing shown in the present example. The arm 13 is provided with a hole(see FIGS. 2, 4, and 5) horizontally aligned with each screw 29. Thelength of each screw exceeds the thickness of the extension 25, and thescrews, therefore, constitute detents projecting from the extensiontoward the arm 13 and into the holes 30. The diameter of the holesexceeds the diameter of the screws, so that during normal operation ofthe relay the screws 29 do not touch the arm 13 and pivotal movement ofthe armature is not interfered with. However, the vertical distance,designated y in FIG. 5, between each screw 29 and the upper edge of itsrespective hole 30 is less than the height, designated x in FIG. 5, ofthe shoulders 22. Consequently, if the armature 11 is lifted off theseat 23, the screws 29 will abut against the upper edge of the holes 30before the shoulders 26 of the armature clear the top edges of theshoulders 22, thereby preventing removal of the armature from the core.To remove the armature from the core, the screws 29 are simply turnedsufficient-ly to extract them from the holes 30; the armature can thenbe lifted 0115 the seat 23 without obstruction. Note that the screws 29need not be removed from the extension 25.

The armature carries a plate 31 of insulation material on its uppersurface. A post 32 projects upwardly from the plate 31, and passesthrough a hole in an arm 33. The arm terminates at one end in a pair ofspaced apart contacts 34, and at the other end in a finger 35 looselyfit into a slot in the plate 31. A bumper 36 projecets downwardly fromthe lower face of arm 33 and bears against the plate 31. A spring 37,surrounding the post 32, normally presses the arm 33 down against theplate 31. A strip 40 of insulation material, mounted on the plate 31 byscrews 42 but spaced above the plate and arm 33 by spacers 41, serves toprevent removal of the finger 35 from its slot. It will be seen,therefore, that the arm 33 is free to pivot about the bump 36 in aclockwise direction in FIG. 2 against the force of the spring 37.

Mounted on the block 15, by means of screws 43, are a pair of arms 44,each carrying a contact at its upper end. The screws 43 also serve asterminals to which an electrical circuit, not shown, can be connected.The contacts 45 are arranged in the path along which the contacts 34travel when the armature 11 pivots from its FIG. 2 position to its FIG.4 position. The armature is normally maintained in a position spacedabove the free end of arm 12, as shown in FIG. 2, by a tension spring 46(see FIGS. 2-4). One end of spring 46 is fastened to a finger 47 struckout of, and hence integral with, the extension 25. The other end of thespring is fastened to a finger 48 struck out of the arm 13, the finger48 passing through an enlarged hole 49 in the extension 25.

When it is desired to mount a relay of the type described on a bus bar,the screws 29 are rotated until they are completely withdrawn from theirrespective holes 30. The armature-tongue 11, 24 is then lifted off theseat 23 to expose the open side of the core 10. The spring 46 may remainsecured to fingers 47 and 48. After insulator members 21 are placedaround the bus bar 17, the core 10 is slipped over the bus bar, andscrews 18 are threaded into pre-tapped holes in the bus bar. Thearmaturetongue 11, 24 is then replaced on the seat 23, and the screws 29returned to the position shown in FIG. 4, thus preventing removal of thearmature from the core. When a current exceeding a preselected valuefiows through the .bus bar 17, the armature 11 pivots about seat 23,against the forces of spring 46, into engagement with the upper end ofarm 12. The contacts 34 are thus brought into engagement with thecontacts 45. The contacts 34 and 45 are so spaced apart that they engagebefore armature 11 reaches arm 12. Consequently, the last portion of themovement of the armature, toward arm 12, causes the arm 33 to pivotabout bump 36 and compress spring 37, thereby insuring good contactbetween the contacts. Obviously, a signal circuit can be connected tothe terminals 43, and energized when the contacts 34 and 45 engage inorder to indicate to an observer that a current exceeding a preselectedvalue is flowing in the bus bar.

The invention has been shown and described in preferred form only, andby Way of example, and many variations may be made in the inventionwhich will still be comprised within its spirit. It is understood,therefore, that the invention is not limited to any specific form orembodiment except insofar as such limitations are included in theappended claims.

What is claimed is:

1. A relay responsive to current flow in a bus bar, comprising aU-shaped metal core adapted to straddle a bus bar, an armature pivotallyarranged at the free end of one arm of said core and extending over thefree end of the other arm of said core, resilient means tending to pivotsaid armature away from the free end of said other arm, a pair of spacedapart electrical contacts mounted for relative movement into engagementwith each other when the current in the bus bar rises to a suflicientvalue to cause said armature to pivot against the force of saidresilient means into engagement with the upper end of said other arm ofsaid core, a pair of upstanding shoulders at the free end of said onearm of said core, said shoulders being transversely spaced-apart anddefining an armature seat between them, said armature having a tongueextending between said shoulders and engaging said seat whereby saidseat serves as a fulcrum about which said armature pivots, a portion ofsaid armature located between said core arms being wider than thespacing between said shoulders whereby said shoulders prevent slidingmovement of said armature in its own plane with respect to said seat,and means limiting the movement of said armature away from said seat toa distance less than the length of said shoulders whereby said armaturecannot be lifted off said seat a distance sufficient to clear saidshoulders.

2. A relay as defined in claim 1 wherein said tongue includes anextension arranged at an angle slightly greater than to said armature,said extension being located adjacent to the outer face of said one arm,and wherein said limiting means includes a detent projecting from saidex tension toward said one arm, and an abutment on said one arm spacedfrom said detent a distance less than the length of said shoulders.

3. A relay as defined in claim 2 wherein said detent is a screw threadedinto said extension and removable therefrom, and said abutment is formedby an opening in said one arm, said opening having a diameter largerthan the dirneter of said screw in order to permit free swingingmovement of said armature, tongue and extension.

4. A relay as defined in claim 1 wherein said armature, tongue andextension are formed of a single initially-fiat metal strip bent to forman angle.

References Cited by the Examiner UNITED STATES PATENTS 1,852,614 4/1932Johnson et al. 1,930,528 10/1933 MaI'thenS 20087 2,341,896 2/1944Bellows et al. 200-87 2,484,863 10/1949 Stillwell 20087 3,177,480 4/1965Sankey 20087 BERNARD A. GILHEANY, Primary Examiner,

B, DOBECK, Assistant Examiner.

1. A RELAY RESPONSIVE TO CURRENT FLOW IN A BUS BAR, COMPRISING AU-SHAPED METAL CORE ADAPTED TO STRADDLE A BUS BAR, AN ARMATURE PIVOTALLYARRANGED AT THE FREE END OF ONE ARM OF SAID CORE AND EXTENDING OVER THEFREE END OF THE OTHER ARM OF SAID CORE, RESILIENT MEANS TENDING TO PIVOTSAID ARMATURE AWAY FROM THE FREE END OF SAID OTHER ARM, A PAIR OF SPACEDAPART ELECTRICAL CONTACTS MOUNTED FOR RELATIVE MOVEMENT INTO ENGAGEMENTWITH EACH OTHER WHEN THE CURRENT IN THE BUS BAR RISES TO A SUFFICIENTVALUE TO CAUSE SAID ARMATURE TO PIVOT AGAINST THE FORCE OF SAIDRESILIENT MEANS INTO ENGAGEMENT WITH THE UPPER END OF SAID OTHER ARM OFSAID CORE, A PAIR OF UPSTANDING SHOULDERS AT THE FREE END OF SAID ONEARM ON SAID CORE, SAID SHOULDER BEING